I bought A&E window awnings from Gamblers in Quartzsite. A buddy and I installed them.
They came with "Oscar" rivets designed for installation on thin material. They are like a regular pop rivet but have slots on the side so they collapse and fold out a larger surface for better retention.
It was not a big job but took a little care to make sure they were level. Gamblers installs a lot of them and recommended that I use a black butyl tape behind the rails instead of regular putty tape. They also recommended I use the next size up screws rather than the what A&E said and stainless steel as well.
After six years of full time use - sometimes in pretty strong winds - they were still working great.
By the way I considered them one of the best add-ons I did for my motor home.